Scanner devices, such as flatbed scanners, are well-known in the art and produce machine-readable image data signals that are representative of a scanned object, such as a photograph or a page of printed text. In a typical scanner application, the image data signals produced by a scanner may be used by a personal computer to reproduce an image of the scanned object on a suitable display device, such as a CRT or a printer.
A typical flatbed scanner may include illumination and optical systems to accomplish scanning of the object. The illumination system illuminates a portion of the object (commonly referred to as a "scan region"), whereas the optical system collects light reflected by the illuminated scan region and focuses a small area of the illuminated scan region (commonly referred to as a "scan line") onto the surface of a photosensitive detector positioned within the scanner. Image data representative of the entire object then may be obtained by sweeping the scan line across the entire object, usually by moving the illumination and optical systems with respect to the object.
By way of example, the illumination system may include a light source (e.g., a fluorescent or incandescent lamp or an array of light emitting diodes (LEDs)). The optical system may include a lens and/or mirror assembly to focus the image of the illuminated scan line onto the surface of the detector. Alternatively, a "contact image sensor" (CIS) may be used to collect and focus light from the illuminated scan region onto the detector.
The photosensitive detector used to detect the image light focused thereon by the optical system may be a charge-coupled device (CCD), although other devices may be used. A typical CCD may comprise an array of individual cells or "pixels," each of which collects or builds-up an electrical charge in response to exposure to light. Since the quantity of the accumulated electrical charge in any given cell or pixel is related to the intensity and duration of the light exposure, a CCD may be used to detect light and dark spots on an image focused thereon.
Flatbed scanners and various components thereof are disclosed in U.S. Pat. No. 4,926,041 for OPTICAL SCANNER of David Wayne Boyd; U.S. Pat. No. 4,709,144 for COLOR IMAGER UTILIZING NOVEL TRICHROMATIC BEAM SPLITTER AND PHOTOSENSOR of Kent J. Vincent; U.S. Pat. No. 4,870,268 for COLOR COMBINER AND SEPARATOR AND IMPLEMENTATIONS of Kent J. Vincent and Hans D. Neuman; U.S. Pat. No. 5,038,028 for OPTICAL SCANNER APERTURE AND LIGHT SOURCE ASSEMBLY of Boyd, et al.; and U.S. Pat. No. 5,227,620 for APPARATUS FOR ASSEMBLING COMPONENTS OF COLOR OPTICAL SCANNERS of Elder, et al., which are each hereby specifically incorporated by reference for all that is disclosed therein.
While flatbed scanners are well-known and are being used, they tend to have a rather large "footprint" thus occupy a substantial amount of space wherever they may be placed (e.g., a desk or a table). Further, since most flatbed scanners need to be connected to various external devices (e.g., wall outlets and personal computers) by one or more cords and cables, most users tend to resist moving the scanner unless absolutely necessary. Indeed, many users tend to regard flatbed scanners as "fixtures" on the desk or table on which they are placed.
Another problem with flatbed scanners is that it can be difficult to scan large items, such as maps or large drawings. Consider, for example, a situation where a user desires to scan only a portion of a large map that is several times the size of the platen (i.e., scan area) of the flatbed scanner. Typically the user will examine the desired area on the map, then turn the map face down on the platen of the scanner. The user may then peel back a portion of the upside down map to check the alignment of the desired portion with respect to the platen. Unfortunately, it is sometimes difficult to confirm correct alignment since the user is looking at the image upside down. Therefore, while this "place and peek" method may eventually yield good results, it usually does so only after several attempts by the user. In the meantime, the user may have wasted considerable time and processing capacity (associated with displaying the scanned image) before the desired portion of the map has been scanned. The chances for success using the foregoing "place and peek" method may also diminish considerably if the portion to be scanned is approximately the same size as the scanner platen. In such cases it is almost inevitable that some slight positioning error will cause a portion of the desired area to extend beyond the bounds of the platen, thus not be scanned.